There are two ways to get there. The first way is a bit longer, as it is a loop, but will offer better views. This longer way is the only way I ever go there. Seems easier to find trails. The shorter way is faster, but will force you to descend a rather steep, sometimes slippery hill. The first way only requires you to scramble up it.
For the loop, begin at the last house on Turner Road. Make your way to the old ATV path located at 13.42891667, 144.704513889. I’ll keep lat/longs like this so you can easily copy and paste into Google.
From here walk the trail southwest toward Mt. Tengo. You will also be heading for the cache Grassy Break, but will break off before getting there. You will soon see a trail on the left about here: 13.42386167, 144.7025.
Turn left and proceed East descending along the ridgeline. This is probably the trickiest part as the sword grass can make it difficult to walk and see landmarks. A map app may help you stay between the correct ravines. It's best to stay just to the left of the hills and close to the top of the ridge. As you approach the falls you may hear water. This is the stream feeding Maguagua Falls. The rock face of the falls is not visible from this direction so don’t be fooled into veering left. Proceed to this point: 13.42512833, 144.70601833. This is the crossroads of the West trail, North trail and the eastbound descent down to the bottom. Look for a ribbon-marked tree. One of the two trees at the top of the main descent has a rope on it. If you are not certain you found the correct tree do not take any steep descents! If you take the faster route you will also arrive here from the North. Carefully head East and look for the path down. There are several ropes to help you make the descent. After the first rope ends the path cuts to the left and then continues down with more ropes.
After reaching the bottom cool off in the shallow pool. If you are feeling adventurous you have some options. While looking at the rock face of the falls look for a ledge about 15 feet up. You can climb up on the left and walk over. Have a sit on the ledge-pool and let the water wash over you. If you are up for it you can also head down river to find the swimming hole. It can be extremely slippery so be careful. There are no more ropes. Expect to be waist-deep at times. You will need to travel about 80-100 yards to reach it. It will also be another 250 feet vertical distance down the descending rocks and small pools. Finding the pool will take a fair amount of time and energy, so make sure you have enough water and food to add this extension, as you will still have to climb out when you are done.
When finished, climb back out to the trail crossroads. Now head north to where you cross the river at the top of the falls here: 13.42531667, 144.70632833. This is also the place for those spectacular views into the valley. When ready, hop over the river at the narrow part and look for the trail heading up the other side. The grass may be long so carefully look for the trail. Scramble up the hill along the faint trail toward this area: 13.42590833, 144.70642222. From here head north-northeast and pick up the trails around Mt. Chachao to head back to Turner Road.
For the faster route you can simple head directly for the falls from the trails around Mt. Chachao to the trail crossroads near the rope path. This may be more difficult in the long run though as finding the path to the rope tree may be obscured.
*Update: I now only recommend you hike down from the North. There is no discernable path the long way anymore.
Finding the cache: As you are descending down the rope path to the bottom of the falls the cache is located beneath a giant asterisk. The cache is a Pelican 1010 Micro Case (6” x 4” x 2”). Please take care to keep the inside of the cache dry. FTF gets an APR Pilot’s Key Chain Computer. Good luck and have fun!
Congratulations to Mcjyvan and ColorfulCumulus for FTF!